The major goal of this project is to develop techniques for studying control of microcirculation in small volumes of tissue by a non-invasive technique. X-ray Spectrometry is being used to study tissue uptake and clearance of non-radioactive substances, such as iodine and xenon. These studies are used to define blood volume and flow under normal, healthy conditions and during induction of inflammation in periodontal tissues in a colony of beagle dogs. In order to make the xenon clearance studies feasible, we are developing a method for reclamation and purification of xenon gas so that it can be used with minimal loss.